1. Field of the Invention
The present invention relates to a wired circuit board, and particularly to a wired circuit board such as a suspension board with circuit or a flexible wired circuit board.
2. Description of the Related Art
Conventionally, for the purpose of reducing a transmission loss in the signal wire of a conductive pattern, a wired circuit board has been proposed which includes, e.g., an insulating layer, a conductive layer covered therewith, and a ground layer disposed to be spaced apart from the conductive layer (see, e.g., FIGS. 8 and 10 of Japanese Unexamined Patent No. 2008-91634).
In the wired circuit board of Japanese Unexamined Patent No. 2008-91634, the insulating layer includes a second insulating layer and a third insulating layer formed thereon, and the ground layer includes a lower ground layer formed under the second insulating layer, a side ground layer in contact therewith, and an upper ground layer formed on the third insulating layer to be continued to the side ground layer.
In the wired circuit board of Japanese Unexamined Patent No. 2008-91634, the second insulating layer and the third insulating layer have a first opening and a second opening which are each formed in the same shape so as to communicate with each other. The first opening and the second opening are each filled with the side ground layer.